The Number Devil: A Mathematical Adventure by Hans Magnus Enzensberger

Synopsis: This is a story about a young boy, Robert, who hates math, yet falls asleep every night and dreams about a Number Devil. The Number Devil is a character who teaches Robert new mathematical terms and theories. Robert and the reader are introduced to new and sometimes difficult concepts. Each chapter of the book represents a new night and a new dream. The book builds upon each chapter and allows the reader to apply previously learned knowledge to the next chapter’s concepts. Throughout the book, explanations by the Number Devil and detailed illustrations help Robert and readers master new material. There are many concepts covered in this book from exponential powers, roots, to even the Fibonacci Sequence.

Review: Algebra and pre-Algebra classes would find this book most helpful, since the concepts align best with those standards. The very last few pages of the book provide an index for the teacher to help find important terms and what chapters to find them in. Detailed pictures provide extra explanation and several chapters even provide extension activities. Overall I found this book to be interesting and useful, but one thing bothers me. Instead of using actual Mathematical terms when explaining ideas, the author uses fictional names for them. For example, “hopping numbers” are what the author calls numbers raised to an exponential power. While he uses the name to help explain the concept, I think the actual terms should be used, to help the students get used to the correct terms and expand their mathematical vocabulary. (Megan M. Frame)

Review: This is an outstanding book that captured my attention fom front to back. There have not been very many books that can gab my attenion; however, Hans Magnus Enzensberger did. There was one thing in this book that I did not like. He used made up words i.e. Rutabagas, instead of the actual word,Square Roots. I believe it is essential for students to know and understand these words. The author did include an index/glossary for teachers/students. The author included several colorful pictures and diagrams to help explain the mathematical ideas and concepts throughout the book. This book would be useful in Algebra and pre-algebra because of the concepts. I like how the author included several extension activities that will provide powerful insight into the concept that were explained throughout the chapter. (David Staszak)

Review: I was very impressed by both the book's story line and its educational value. The story is enough to keep most readers engaged, and it is obviously an excellent way to introduce certain topics to the classroom. The additional activities included in some chapters were also of great assistance. However, I did not like the way the author made up names for mathematical terms instead of using the actual word. While the glossary in the back did help with this issue, it still would have made things clearer if the proper term had been used in the first place. (Jessica Goodrich)

Review: This book was a lot of fun to read. I enjoyed the concept and was wondering what topic the number devil was going to cover next. The number devil did a wonderful job of explaining difficult concepts in a way that was easy for the math-phobic person to understand. The one thing that I did not like about the book was the name the number devil gave to his concepts. They were not the names that we know for example, instead of square numbers he called them hopping numbers. At the end of the book the author did state that the names given are not names your parents or teachers will know so don't use them, but most children don't read that section of a book. (Laura Chapman)

Lesson Idea # 1:
Chapter 6 and 7 of the book introduces and analyzes the Fibonacci triangle, as well as illustrates different patterns to the students. At the start of the class, the students can be asked to quickly read chapter 6, then discuss what they understand about the reading. The teacher can then help students understand any information they struggle with. Students are then split into groups and each group is asked to read a different part of Chapter 7. Once the groups finish their section, one by one they can explain what their part is about, each illustrating a different pattern found in the Fibonacci Triangle. The extension activity at the end of chapter 7 can be used in groups if needed, or assigned as homework.

2: Chapter four introduces powers including square roots. In the beginning of class, the students can begin to read the chapter. However, when they come to the square roots, have the students stop reading. Break the clss into groups of three or four and give each group 8 yard sticks. Have them construct a square with lengths of 1 foot. Have the students create the diagnol of the triangle and ask if anyone knows the length of the diagnol. Have the students create a square using the diagnol of the smaller triangle. Have the students create both diagnols of the larger triangle. Showing the students that two of the smaller triangles can fit in the new triangle. See if the students can figure out the length of the first diagnol. After there is a class discussion, continue reading the chapter. Try to possibly connect it to pythagorean theorem

Lesson Idea #3
Chapter 9 introduces the concept of the infinite series. Students would read the chapter and then additional examples of series could be given. (For instance, a series that contained the "hopping" numbers.) The students would then be broken into groups. Each group would be given the task of coming up with their own infinite series. After the groups were done, they would switch series with another group and determine what number, if any, the series converged on.

Lesson Idea #4
One of the concepts that I know a lot of students struggle with is prime numbers. I liked how the number devil showed Robert how to find the prime numbers. The class is do a smilar idea to understand which numbers are prime and which are composite. THe teacher could make a table of all the numbers atleast up to 100. Then together they can cross of the numbers they know are composite until they are left with only prime numbers. FIrst take number 2 which is prime, then remove all multiples of 2 since they cannot be prime. Continue this process for the other numbers as well.